title: Activation of XerCD-dif recombination by the FtsK DNA translocase.
abstract: The FtsK translocase pumps dsDNA directionally at ∼5 kb/s and facilitates chromosome unlinking by activating XerCD site-specific recombination at dif, located in the replication terminus of the Escherichia coli chromosome. We show directly that the γ regulatory subdomain of FtsK activates XerD catalytic activity to generate Holliday junction intermediates that can then be resolved by XerC. Furthermore, we demonstrate that γ can activate XerCD-dif recombination in the absence of the translocase domain, when it is fused to XerCD, or added in isolation. In these cases the recombination products are topologically complex and would impair chromosome unlinking. We propose that FtsK translocation and activation of unlinking are normally coupled, with the translocation being essential for ensuring that the products of recombination are topologically unlinked, an essential feature of the role of FtsK in chromosome segregation.
authors.affiliation: Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK. ian.grainge@newcastle.edu.au
authors.forename: Ian
authors.initials: I
authors.lastname: Grainge
authors.forename: Christian
authors.initials: C
authors.lastname: Lesterlin
authors.forename: David J
authors.initials: DJ
authors.lastname: Sherratt
mesh_terms: D002876:Chromosomes, Bacterial / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D045566:DNA, Cruciform; D004789:Enzyme Activation; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019426:Integrases / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic; D017384:Sequence Deletion
chemical_list: D045566:DNA, Cruciform; D029968:Escherichia coli Proteins; C096452:FtsK protein, E coli; D008565:Membrane Proteins; C473360:XerC protein, E coli; D004247:DNA; D019426:Integrases; C473361:XerD protein, E coli